Sound-reproducing device



Jur'xe 3, 1930. L. M. CLEMENT v I 1,762,090

` soUND REPRODUQING DEVICE Filed June 13, 1927 3 Sheets-Sheet 1 if ggg IN1/gmx.

BY l Z 2 j )ZM TToRNEYs.

m N.. m

ATTORNEYS.

June 3, 1930. M, CLEMENT SOUND REPRODUCING DEVICE Filed June 13, 1927 Jupe 3, 1930.` yl.. MQ CLEMENT '1,762,090 7 SOUND REPRODUCING DEVICE Filed'June 15-l 1927y v :s sheets-sheen s #cui ATTORNEYS.

BY W

laitented 'June 3, 1930 UNITED STATES PATENT OFFICEl LEWIS M. CLEMENT, OIi MOUNTAIN LAKES, NEW JERSEY, ASSIGNOR TO F. A.. ANDREA, INC., OF NEW YORK, N'. Y., A CORPORATION OF NEW YORK SOUND.REIPROlDlJ'CING: DEVICE ppHeation led J'une 13,

My invention relates to sound reproducing devices generally known as loud speakers. My invention relates specilically to a device of this character having a sounding board or sound radiator as distinguished from the sound box and hdrn type of such device.

- My invention will be better understood by reading the following description in connection with the accompanying drawings, vin l0 which Fig. 1 is a vertical section of a device embodying my invention;

Fig. 2 is a section on line II-Il of Fi 1;

Fig. 3 is a sectional view of a part 'o the motor unit;

Fig. 4 is a 'vertical section of a modifica-v tion of the invention; l

Fig. 5 is avvertical section of a further modification of the device;

Fi `6 is a center section through a modied crm; land Fig. 7 is a front elevation of the form shown in Fig. 6.

Referring to the drawings, the device con- 25 sists of a standard or support 1 of an suitable design.` Attached to the stan ard 1 are a number of horizontal supports 2 (in this case five). .These supports may be attached to the standard by screws 3 0r may be made integral therewith. The motor 4 may be mounted on two parallel bars, one of which is shown at4 5. 1 The motor unit may be carried by side members 6 shown in section in Fig. 3. Any form-of motor unit may be used.

The sounding board or sound radiator is carried by the supports 2. The sounding board or sound radiator illustrated in Fig. l consistsv of a conical member 7, a frusto' conical member 8 and a baiie 9. The peripheries of the members 7, 8 and 9 are fastened together preferably by layingA them Aagainst each other and placing a piece of braid 10 over them and 'stitching all of the arts in place as at 11. This construction orms a suitable union between the parts which is more durable than any of the forms of gluing or cementing. When the parts are in position on the supports the baile 9 lies in a plane at right angles to the longitudinal axis 1927. Serial No. 198,371.

of the members 7 and 8. The members 7, 8 and 9 are supported by the supports 2 by means of screws 12 -which pass through the baile 9 and enter the ends of the supports 2. The edge 13 of the frusto-conical member 8 55 is free and unsupported.l If desired this edge may be provided with some form of damping means to prevent rattling. By supporting the sounding board or sound'radiator through the baiiie 9 in the manner 60 shown and described it is supported at approximately its center of mass, which avoids any tendency on the part of the diaphragm to be distorted due to its own weight, an is free to respond to vibrations which are imparted to it by the motor unit through the member 14 which is attached to the apex of the member 7. by any suitable clutchin or fastening vmechanism 15. A conical sti ening member is snugly fitted into the apex of the conical member, as will be explained in detail later. The driving member 14 is fastened to a pivoted transformer. member 16 which is constructed vso as to be as rigid'as possible in its plane of movement and which is pivoted around beari`ngs17 to a bracket 18 fastened onto the member 19of the mo; tor unit. The driving rod 14 is flattened at 14a so`as to allow it to bend in a plane passing through the longitudinal axis of the i transformer member 16 and the rod 14. The bearings 17 are between the ends of a hard pin 17i and openings in the upturned ends of the member 18. The member 16 1s connected with the armature 20 of themotor 35 unit through a member 21, having flattened portions 21 to allow member 21 to .bend readily. The armature is under the influence of the permanent horseshoe. magnet .22,

and also the electromagnetic coil 23 wh1ch 9 y is actuated by the sound current impulses to be reproduced. 4

The baie 9 is provided with an opening 24. The size of the opening 24 in the baie 9 may be varied to secure the desired results 95 as to damping by controlllng the air movement resulting from the actuation of the 'sounding board.

Referring to the modication shown 1n Fig. 4, simllar parts are marked with the 10 same numbers with the exponent a attached. In this modication the conical member 7al is separate from the frusto-conical member 8 thereby providing a space 25 between the peripheries of themembers 7a and 8". This arrangement provides. a lighter sounding board or sound radiator. The frustum 8a is rigidly attached to the standard 1 and may be provided on its inner face with a lining of elt 26 or other non-reflecting absorbent material to prevent refiection of sound. The cone 7a is supported at approximately its center of mass by flexible members 27 through which screws 28. pass into the supports 2. This cone is 'also preferabl provided around its periphery with a sti ening member 29 to dampen the periphery of the cone.

The periphery of the diaphra m 7, 7b, Figs. 4 and 5, may be bound withgbraid for mechanical protection. vThe braidmay be sewn as shown in Fig. 1. The braid may also act as a damping means for the ey riphery, but if the cone is suiiiciently sti it is not necessary for proper operation of the diaphragm. The diaphragm may be otherwise loaded to change its frequency characteristic in the desired manner, this loading dampening ring may, be applied to any portlon of the diaphragm? and it may be located either concentric with or eccentric to the center or apex (see Fig. 6). By roper choice of the diameter, width an mass of the ring and the proper location of it with respect to the apex, the response characteristic of the diaphragm may be modified as desired. The loading of the outer ortion of the diaphragm in general afects the lower frequency and indirectly the higher frequency. The eccentric loading or dampening ring affects the wave which may be set up inthe diaphragm and would otherw1se cause out-of-phase radiation. The above may be applied to any type of diaphragm to improve or modify the response frequency characteristics. The cone is free to respond to the vibrations of the motor elements 14a because ofthe flexibility of the members 27. The eifect of the frustrum 8aL upon the action of the device may be varied by varying the opening 25. I have shown a further modication o my invention in Fig. 5, in which the same 55. parts bear the same numbers with the exponent 'b attached. This modification is quite similar to that shown-in Fig. 4, the chief difference being that thejperiphery ofthe frustum 8b is curled over the periphery of the cone 7b.

In Figs. 6 and 7 are shown two views of "a further modification of my invention. In

, eccentric damping means acts somewhat dif.:

' may be also ferently from the concentric damping means 'I 29, shown in Fig. 4. A Y

In this embodiment of the invention a reinforcement of paper, aluminum or other light material may be placed in the apex of the cone in order to render it strong and stiff. A light aluminum reinforcement may be cemented or otherwise fastened to the diaphragm and a light vchuck 15 riveted in place. The aluminum or other li ht reinforcement increases the eiiiciency o the diaphragm at the higher 'equencies. The response characteristic of the diaphragm may be changedI by the proper placing' of annular stiii'ening rings or ribs 31 in the stii'ening member 32. The annular stiii'ening ribs in the stiff conical reinforcing center piece allow this piece to be broken into a stiff central portion flexibly connected to the other outer portions by means of the annular ribs. The paper or other material used as the diaphragm provides damping means between these annular portions of.

the central stifenin cone. This construction increases the e ciency at the high frequencies by providing a diaphragm whose mass at high frequencies is lessened by partial isolation of the central portion of the diaphragm.

By the combination of the loading rin s 29, either concentrically or eccentrica y placed, of proper width and mass and by the placing of the light stifi'ening cone of proper size at the apex of the diaphragm the eiiciency of the diaphragm may be increased at'certain frequencies due to the fact that the impedance characteristic of the diaphragm can be changed as 'desired by th stiffening and .loading means In general the smaller the diameter of the small central stifl'ening cone, the higher the frequency radiated from the diaphragm, and loading the outer edge of the diaphragm helps in the radiation of the low frequencies. Increasing the mass in general improves the eiciency at the lower frequencies.

The dissymmetrical loading of the diaphragm because of the abrupt change in constants of the diaphragm at the boundary of the loading causes reflection at those points, and because the distance from the center to these points-is different, standing waves will not be set up to the extent they are with the circular diaphragm.

The diaphragm shown in Fi sl 1, 4 and 5 rovided with sti ening means at the apex or the reasons just explained.

The eliciency of the flexible mountings on the front Aof the diaphragm may be increased by stiiening the material of the cone around the edgesof the holes in the diaphragm'by means of ribs, as shown in Fig. 6. These ribs may consist only of the material of the diaphragm, or if desired, lmetal such as aluminum may be attached to the diaphragm and made to conform with the shape shown in F ig. 6.

In Figs. 6 and 7 a stiffening annular rib 30 is formed at the periphery of the diaphragm. If desired such a rib may be provided at the periphery of the diaphragm shown in Figs. 2, 4 and 5.

By the constructions above shown and described faithful reproduction of sound is produced at a higher eiiiciency than has been possible heretofore. The mechanical transformer from the armature 20 to the cone 7 is highly eiicient because of the rigidity of the member 16, the ease with which the same may be moved around its pivot bearings 17 and the other elements of design shown and described. The sounding board or sound radiator is free to respond to the vibrations of the motor unit lbecause of its bein supported approximately at its center o mass which renders it free from any tendency' of distortion due to its own weight. -Other points of advantage will be apparent -to those skilled in the art. 4

I claim:

1. A sound reproducing device comprising a flexibly supported sounding board, a motor for actuating said sounding boardand a exible baiie for regulating the movement of air produced by the actuation of said sounding board and acting as the support for the sounding board.

2. A sound reproducing device compris-4 ing a conical sounding board element, a

motor for actuating said element from the 'apex and la conical stiiening member snugly fitted intothe a eX of the sounding board element, said sti ening member hav ing stiiening rings.

3. A sound reproducing device comprising a conical member and a frusto-conical member, said membersl being fastened together at their peripheries and a bailie fastened to said membersand lying in a plane at right angles to the longitudinal axis of said members, means for supporting said device through said baille and a motor for actuating said device.

4. A sound reproducing device comprising a conical member and a frusto-conical member, said members being fastened t0- gether at theirperipheries and a bale fastened to saidl members and lying in a plane at right angles to the longitudinal axis of said members, means for supporting said device through said bailie and a motor for actuating said device, and an opening through said baiile for controlling the movement of the air agitated by said device.

' LEWIS M. CLEMENT. 

